Microencapsulated liquid membrane

HFCLM hollow-fiber contained liquid membrane MELM microencapsulated liquid membrane... 

Microencapsulation can be used to provide a temporary barrier between a chemical species and its surrounding environment see also Section 14.3). This permits controlled (slow) release of the active agents following application. Depending on the product and the situation, an active ingredient such as a pesticide may need to be released slowly at low concentration, or slowly at high concentrations. Such controlled release can both reduce the number of crop applications that are required and also help prevent over use and subsequent run-off. The barrier can be provided by a polymer film, in the case of suspensions [867], or a liquid membrane, in the case of single or multiple emulsions [865], Microemulsions have also been used [234,865],... 

Several immobilization techniques have been developed to overcome the instability problems of SLMs, such as by the gelation or microencapsulation of the liquid phase, covering the surface layers (contained liquid membranes). An overview on stabilization techniques for SLMs developed over the last 10 years can be found in Ref. [126]. 

The most important physical methods are physical and ionic adsorption on a water-insoluble matrix, inclusion and gel entrapment, and microencapsulation with a liquid or a solid membrane. The most important chemical methods include covalent attachment to a water-insoluble matrix, cross-hnking with the use of a multifunctional, low-molecular weight reagent, and co-cross-linking with other neutral substances, for example proteins. 

Microencapsulation means the envelopment of liquid droplets or solid particles with natural or synthetic polymers.The encapsulation of a substance with a polymer membrane is undertaken for various reasons, for example, as protection against moisture, or to obtain delayed dissolution of fertilizers, herbicides, or drugs by microencapsulation with semipermeable membranes. 

Typical is microencapsulation , a method by which small portions of liquids, particulate solids, or gases are surrounded by a shell (membrane, capsule) to form approximate spherical particles. 

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